Cardiac electrotherapy leads are implanted within various locations of a heart to provide pacing and/or defibrillation electrotherapy. Cardiac perforation of the right ventricle (“RV”) wall is a risk associated with all transvenous lead implantations to the RV apical site, especially active fixation leads, leads with smaller diameters, and defibrillation leads. The likelihood of perforation is a function of the lead and/or stylet configuration and the dexterity of the implanting surgeon.
In rare cases, the distal end of a lead acts as a spear that pierces the RV wall, either during implantation of the lead or in the succeeding months. If a lead perforates the myocardium, acute patient symptoms can include pericardial effusion, cardiac tamponade, pericarditis, or even death. Additionally, a lead that has perforated the myocardium may be non-functioning and may cause chest pain or pneumothorax.
The RV apical wall can be as thin as one millimeter thick, and the right atrium (“RA”) appendage can be less than one millimeter thick. In contrast, a helix extending from the distal tip of a lead can be two millimeters long when fully extended. As a result, it is possible for the helix to cross the entire thickness of a RV apical wall or a RA appendage wall.
There is a need in the art for an implantable cardiac electrotherapy lead configured to reduce the likelihood of cardiac perforation. There is also a need in the art for a method of making and deploying such a lead.